At present, high-performance on-road sports cars are normally rear-drive, and have a self-locking differential to increase the drive torque transmitted from the rear wheels to the road surface.
A rear drive with a self-locking differential has its advantages when driving fast in good (dry) or at least acceptable (wet) road-holding conditions, but, combined with a high drive torque and oversized tyres, makes for extremely difficult, and therefore potentially dangerous, driving in poor road-holding conditions (flooding or ice).
To make driving easier in poor road-holding conditions, it has been proposed to equip high-performance sports cars with a permanent or connectable four-wheel drive.
A permanent four-wheel drive greatly improves vehicle performance in poor road-holding conditions, but has the drawbacks of permanently increasing torque loss of the drive system, and of imposing vehicle performance which drivers do not always find suitable in good road-holding conditions.
A connectable four-wheel drive allows the driver to choose between a rear drive and a four-wheel drive, and so use the rear drive in good road-holding conditions, and the four-wheel drive in poor road-holding conditions. A connectable four-wheel drive, however, is complex and therefore expensive to produce. Moreover, the driver may fail to see ice on the road, and so fail to connect the four-wheel drive in time.